Search

This paper describes the development of a finite-element model capable of representing a blast-resistant flexible window (flex window) system developed by the Air Force Research Laboratory/Airbase Technologies Division. Computational fluid- structure interaction finite-element simulations are used to develop an improved understanding of the manner in which fluid phenomena, such as air compression and flow, affect the behavior of the flex-window system under blast loading. Compressible airflow interacting with a flexible thin-shell structure of the flex window (transient air-window panel interaction phenomena) is found to significantly influence system performance. The influences of shock wave propagation and fluid venting inside the damping chamber of the flex-window system are quantified and the influences of such phenomena on panel deflections, deformations, and internal forces are presented. DOI: 10.1061/(ASCE)ST.1943-541X.0000100 CE Database subject headings: Blast loads; Finite element method; Dynamics response; Computer models; Fluid-structure interactions; Full-scale tests. Author keywords: Blast loading; Finite element method; Dynamics response; Computer models; Fluid-structure interaction; Full-scale tests.

This paper presents a thermoeconomic optimization analysis yielding a simple algebraic formula for estimating the optimum number of panes for windows. The '[P.sub.1]-[P.sub.2] method,' 'the degree day method,' and 'the equivalent full load hours energy estimation method' are used together with the correlated overall heat transfer coefficient values for single, double, triple, and quadruple pane windows that are used in HVAC and refrigeration applications. CE Database subject headings: Optimization; Windows; Thermal factors.

Abstract: To estimate the energy performance of windows, the seasonal accumulated solar heat gain through the windows has to be calculated. A simplified method for calculating seasonal accumulated solar heat [...]

Abstract: This study outlines a simplified mathematical approach to determine window dimensions for a given room based on two lighting quality indicators, namely, discomfort glare and vertical illuminance. The former [...]

Byline: Po-Cheng Chou (Department of Interior Design, Shu-Te University, Kaohsiung County, Taiwan, paul@mail.stu.edu.tw); Che-Ming Chiang (Department of Architecture, National Cheng-Kung University, Tainan, Taiwan); Yen-Yi Li (Department of Interior Design, Shu-Te [...]

Current multi-pane windows have a very low heat loss but their solar transmittance is low resulting in a loss of daylight and solar gains. Multi-pane windows also require framing arrangements that are difficult to retrofit to existing apertures in many existing buildings. A contiguously sealed evacuated double-glazing with low long-wave radiative emittance coatings on its internal surfaces, no heavier than conventional double-glaring, with good visual transmittance suitable for retrofitting to existing buildings, has been analyzed experimentally. Measured heat transfer coefficients and visual transmittances of laboratory fabricated evacuated glazing samples, along with theoretical predictions of center of glazing thermal conductance are presented. [DOI: 10.1115/1.2188529] Keywords: fenestration, insulation, window, glass, energy efficiency

Daylighting supports human activities with energy savings and provides positive effects to human health. In a dense urban environment, ensuring adequate daylight incident on windows is of the utmost importance [...]

The 'supply air' window is in essence a modified Scandinavian 'double' window having outer and inner sashes with a gap between them forming a route for the ingress of ventilation [...]

Explosive attacks on buildings create a rapid release of energy in the form of a shock wave. Window glass is often the weakest part of a building, breaking at low pressures compared to other building components. Explosion-related injuries caused by glass breakage include eardrum damage, lung collapse, and penetration- or laceration-type injuries from airborne glass fragments which may lead to fatalities. As glass breakage may extend for miles for a large external explosion, reducing glass hazard is an important aspect of blast-mitigation for buildings. Blast-mitigating window products are in their infancy in the United States. Categories of available window retrofit solutions include: window film technologies, mullion and frame upgrades, catch systems, window replacement systems, installation of secondary windows, and/or a combination of these technologies. Installation of daylight film is the least costly but provides the lowest level of protection, while replacing windows is the most costly with the greatest gain in blast protection. Selection of the best window retrofit solution is usually based on a number of design constraints including blast criteria, building constraints--which can be broken down into type of building, maintenance and operability requirements, interior finishes, energy conservation requirements, lifecycle--and finally the retrofit cost. CE Database subject headings: Blast effects; Window glass; Terrorism; Explosions; Retrofitting.

Building design should aim at achieving comfort conditions and minimizing the energy consumption. The visual comfort conditions are given as the required levels of illumination, glare avoidance and a uniform [...]

This paper describes a simplified dynamic thermal model which simulates the energy and overheating performance of windows. To calculate artificial energy use within a room, the model employs the average [...]

'Supply Air' windows work as a heat reclaim device by intercepting a substantial proportion of incident solar energy as well as entraining heat escaping from rooms. This series of experiments [...]

This study suggests an approach for determining the most suitable types of external shading devices that will allow an optimal view of the exterior for windows with various orientations. In [...]

The cooling cost of buildings in the summer season may be reduced by structural changes and/or repositioning of windows so that window panes are inclined to the inside, and the [...]

The basic design guidelines for a window and facade glass which rejects direct solar radiation during the summer period and which transmits direct solar radiation during the remainder of the year are derived. The design employs purely passive control means and is based on the seasonal change of the incident angle of solar rays and on the capability of glass prisms to refract and totally reflect or transmit solar rays dependent on the relevant incident angle. Two new design elements essentially extend the applicability of the glass in accordance with window orientation and season of direct solar light rejection.

The theory and predicted performance of a new type of glazing exhibiting strong angle-selective reflectance and high viewing transparency are presented. The glazing comprises a fixed venetian blind style arrangement of laser-cut panels. The theory shows that the transition from high transmittance at near normal incidence to high reflectance at larger incident angles can be varied in magnitude and over a wide angular range by altering the laser-cut spacing and panel spacing. Calculated radiant transmission and daylighting performance for the glazing on southern and east/west facades in buildings at temperate and sub-tropical northern latitudes predicts excellent performance for a single practical configuration of the system.

Angular selective glazing based on special obliquely deposited thin films, has considerable potential for optimizing the overall performance of a window in temperate to hot climates. In contrast to most currently used glazings for these environments it has the ability to control solar heat gain and glare while providing a clear view through the window and considerable but not excessive light gain. Various deposition techniques and film materials will be discussed and the spectral and integrated optical performance of single and double-layered systems presented for various directions of incidence. Full optical characterisation requires measurements for incidence directions over half a hemisphere. Some of this is presented but most data is confined to planes of incidence where angular selectivity is greatest as determined by deposition geometry. Two layer systems are designed to provide a low emittance and better solar control than the single layer systems while retaining good visible angular selectivity. The single layers are primarily to provide angular selective control of the visual radiation since they have moderately high transmittance in the near infrared and a high emitrance. Theoretical models used to extract structural information and model the complex optical properties are introduced and their predictions assessed. Preliminary results on simulation of the performance of full size angular selective windows in comparison to other types of solar control glazing such as low e heavily tinted windows are discussed in terms of their relative impact on cooling load, lighting contribution, glare control and total energy savings.

Modern, energy-saving buildings incorporate large areas of highly insulating glazing. The resulting solar gains lead to major savings in heating energy during winter, but protection against overheating in summer is also needed. Usually this problem is solved by using mechanical shading devices, with the disadvantages of high cost and low durability. The work on switchable glazing at Fraunhofer Institute for Solar Energy Systems, in cooperation with industrial partners, aims to present new and viable alternatives. Two types of switching layers, which are quite different in their structure and function, but are similar in having a large dynamic range in TSET, are being investigated gasochromic and thermotropic. Gasochromic windows are actively switched between a clear and a coloured (but image-preserving) state by alternately introducing strongly diluted [O.sub.2] and [H.sub.2] gases. In contrast to classic electrochromic configurations, only one tungsten oxide film with a very thin catalyst coating is needed. At present, prototype windows with an area of 1.1 x 0.6 [m.sup.2] are being produced by sputtering. Careful adjustment of the layer structure, the gas concentration and its flow velocity is needed to obtain the desired switching rate. Homogeneous colouring of the whole area within seconds has been achieved. In addition to information on the colouring kinetics, the paper also discusses system aspects of these windows. Thermotropic layers switch reversibly and automatically, from a clear state with high transmittance to a milky white state with high diffuse reflectance, when their temperature rises. Depending on the composition of the material, the switching temperature can be chosen in the range needed. The measured optical properties of glass laminates with a thermotropic layer are presented. These are combined with the measured values for further panes to calculate the characteristic data for thermotropic insulated glazing units. The results are compared with those measured on a 1.1 x 1.65 [m.sup.2] prototype window. Stability results are also included. The effect of the two different types of switchable glazing on building energy savings is explored for a residential building model, using the TRNSYS building energy simulation program.

Summer cooling loads in buildings can be reduced with windows of low solar heat gain coefficients (SHGC). Such windows are often double glazed with the exterior pane tinted or selectively absorbing. They reject part of the absorbed solar radiation to the environment, reducing the solar heat gain. This effect is undesirable in the cold season. However, the same window installed in reverse, i.e. turned by 180 [degrees], has a significantly higher SHGC. Thus, windows that can be reversed according to the season will both reduce summer heat gains and collect much of the beneficial solar radiation in winter. This paper investigates the energy savings achievable by reversing equator-facing windows for the duration of the cold season as opposed to leaving them in the 'summer position'. Candidate climates in which these savings may be significant are identified. By means of a computer simulation, seasonal energy savings are predicted for a model room with reversible, low SHGC, windows. The results indicate that for suitable climates, significant savings are achievable.

In the course of the development of a domed magnesium fluoride detector window for the Space Telesco Imaging Spectrograph, slated to be a second-generation instrument aboard the Hubble Space Telescope, sample window materials from various commercial sources displayed a wide variability in vacuum ultraviolet transmittance. As a result a test program was undertaken in cooperation with the supplie prototype domed window to maximize transmittance. Results of the program have provided clues to the causes of the variations experienced, and they point to careful selection of raw materials and stric control to achieve optimization. Key words: Transmittance, magnesium fluoride, windows, vacuum ultraviolet., Sample window materials from variuos commercial sources were found to have a wide variability in vacuum ultraviolet transmittance during the development of a domed magnesium fluoride detector window for the Spcae Telescope Imaging Spectograph. To maximize this transmittance capability, a test program was undertaken together with a prototype domed window supplier. Program results led to ideas on the causes of the variations experienced. It was also proven that optimization is possible with careful selection of raw materials and strict process control.

Fire Spreading of Materials and Its Contribution to Compartment Fire Thesis for the degree of Doctor of Philosophy Department of Building Services Engineering, Hong Kong Polytechnic University, Hong Kong, China [...]

Byline: Inderjeet Singh, N.K. Bansal Windows in a building allow daylight to enter a building space but simultaneously they also result in heat gains and losses affecting energy balance. This requires an optimisation of window area from the point of view of total energy demand viz., for lighting and cooling/heating. This paper is devoted to this kind of study for Indian climatic conditions, which are characterised by six climatic zones varying from extreme cold to hot, dry and humid conditions. Different types of windows have been considered because the optimised size will also depend on the thermo-optical parameters like heat transfer coefficient (U-value), solar heat gain coefficient (g), visual (I), and total transmittance (T) of the glazing in the window. It is observed that in a non-insulated building, cooling/heating energy demand far exceeds lighting energy demand, making the optimisation of window area a futile exercise from the point of view of total energy demand. Only for buildings with U-value below 0.6 W/mOK can optimisation be achieved. The optimised window area and the corresponding specific energy consumption have been calculated for different climates in India, for different orientations, and for three different advanced window systems.

The activity of designing a window for an art museum is explained. Through this activity the students are exposed to the real-world problems of the design process along with their solutions.

The shading system includes a plurality of shading elements forming groups of elements for each window of a building. The elements generally have non-horizontal and non-vertical slope and tilt angles. The slope and tilt angles are determined by the latitude of the building and compass bearing of a plane through the window. All of the elements for each window lie parallel to one another and are nonmovable. By calculating slope and tilt angles for each compass bearing and building latitude, the solar heat gain in the summer can be minimized and solar heat gain in the winter can be maintained.

A skylight provides natural light, energy savings, and comfort. School administrators who are selecting skylights should consider the use of glazing to control solar heat gain in the buildings.

A nurse who helped design windows that allow a secure unit to be fully ventilated for the first time expects them to be adopted by other hospitals after an exhibition [...]

Insulated glass windows enable housing managers to reduce their energy costs.Based on the American Architectural Manufacturers Assn's formula for computing heat loss, it was found that it costs an additional $6.72 to heat each 12 square-foot pane of glass of non-insulated windows than it does to heat insulated ones. However, if the hermetic seal in the window fails, replacementscan cost between $35 to $85. One solution to this problem is using a combination of prime and storm window. Although opening and closing these windows can be difficult. A second alternative is using a mechanically sealed window. Such windows remove the possibility of hermetic seal failures and allows the use of unbreakble polycarbonates instead of regular glass. On the other hand, a 'tilt-in cleaning' window is also available which allows the outside of the window to be cleaned from the inside.